The Effects of Temperature and Some Inhibitors an the Carnitine Exchange System of Heart Mitochondria

Rona R. Ramsay*, Philip K. Tubbs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

11‐Trimethylamino‐undecanoyl‐l‐carnitine (K; = 56 μM) and 6‐trimethylaminohexanoyl‐l‐carnitine (K1, = 1.3 mM) are competitive inhibitors of the ox heart mitochondrial carnitine exchange system. The latter is itself a poor substrate, with a V about 0.7 of that for carnitine. These compounds have been'used as ‘stop inhibitors’ in a study of the effect of temperature an the carnitine exchangc. The carnitineout↔ H carnitinein exchange has a temperature coefficient (Q10) of 8.5 and an activation energy of 176 kJ/mol which is constant from 0 °‐18 °C. The Km for L‐carnitine (5.3 mM) is also constant over this temperature range. The slow efflux (leak) of mitochondrial L.‐[14C]carnitine in the absence of external substrate has a similar temperature dependence and is also inhibited by 11‐trimethylamino‐undecanoyl‐L‐carnitine. lt is probably mediated by the same system as the very much Taster exchange with external carnitine

Original languageEnglish
Pages (from-to)299-303
Number of pages5
JournalEuropean Journal of Biochemistry
Volume69
Issue number1
DOIs
Publication statusPublished - 1 Jan 1976

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